Technical Field
The present invention relates to a method for preparing a gallium-doped zinc oxide electrode decorated with densely gathered palladium nanoparticles having electrocatalytic applications.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
In recent years, transparent conducting oxides (TCOs) have been used in a variety of optoelectronic devices, including flat panel displays and solar cells due to their good electrical conductivity, high transparency in the visible light region, and stability. See Y. C. Lin, T. Y. Chen, L. C. Wang, and S. Y. Lien, “Comparison of AZO, GZO, and AGZO thin films TCOs applied for a-Si solar cells” Journal of the electrochemical society, 159 (2012) H599-H604, M. Li, C. Kuo, S. Chen, C. Lee, “Optical and electric properties of aluminum-gallium doped zinc oxide for transparent conducting film” Proc. SPIE 7409, Thin Film Solar Technology, 74090W, (2009) doi:10.1117/12.825206, and Z. C. Chang, S. C. Liang, “The microstructure of aging ZnO, AZO, and GZO films” International Journal of Chemical, Nuclear, Materials and Metallurgical Engineering 8 (2014) 422-424, incorporated herein by reference in their entireties. Indium tin oxide (ITO) is the most common TCO electrode material; however, because the indium supply is limited, the development of alternative TCOs is desirable. See M. A. Aziz, M. Sohail, M. Oyama, W. Mahfoz, “Electrochemical investigation of metal oxide conducting electrodes for direct detection of sulfide” Electroanalysis, 27 (2015) in press, doi: 10.1002/elan.201400539, M. A. Aziz, T. Selvaraju, H. Yang, “Selective determination of catechol in the presence of hydroquinone at bare indium tin oxide electrodes via peak-potential separation and redox cycling by hydrazine” Electroanalysis 19 (2007) 1543-1546, M. A. Aziz, M. Oyama, Materials for Biomedical Applications, “Trans Tech Publication Inc.” (2014) pp. 125-143, M. A. Aziz, S. Patra, H, Yang, “A facile method of achieving low surface coverage of Au nanoparticles on an indium tin oxide electrode and its application to protein detection” Chem. Commun. (2008) 4607-4609, P. Bertoncello, M. Peruffo, P. R. Unwin, “Formation and evaluation of electrochemically-active ultra-thin palladium-Nafion nanocomposite films” Chem. Commun. (2007) 1597-1599, M. A. Aziz, S. Park, S. Jon, H. Yang, “Amperometric immunosensing using an indium tin oxide electrode modified with multi-walled carbon nanotube and poly(ethylene glycol)-silane copolymer” Chem. Commun. (2007) 2610-2612, M. Oyama, Recent nanoarchitecture in metal nanoparticle-modified electrodes for electroanalysis, Analytical Sciences 26 (2010) 1-12, B. Kim, D. Seo, J. Y. Lee, H. Song, J. Kwak, “Electrochemical deposition of Pd nanoparticles on indium-tin oxide electrodes and their catalytic properties for formic acid oxidation” Electrochemistry Communications, 12 (2010) 1442-1445, and S. Hussain, K. Akbar, D. Vikraman, M. A. Shehzad, S. Jung, Y. Seo, J. Jung, “Cu/MoS2/ITO based hybrid structure for catalysis of hydrazine oxidation” RSC Adv. 5 (2015) 15374-15378, each incorporated herein by reference in their entirety. Zinc oxide (ZnO) is a strong alternative candidate, as it is inexpensive, non-toxic, and abundant. The poor electrical conductivity of ZnO has led to the exploration of aluminum-doped ZnO (AZO) and gallium-doped ZnO (GZO) for use in optoelectronic devices.
ITO has been widely used in electrochemical voltammetric studies as a base electrode material onto which metal nanoparticles (NPs) may be deposited. AZO and GZO, on the other hand, have not been examined extensively in voltammetric analysis, due to the poor electrocatalytic properties of AZO and GZO toward many electroactive molecules. Modification of AZO and GZO electrodes with metal NP electrocatalysts has not been explored previously.
PdNPs have raised considerable interest in electrocatalytic applications due to their excellent electrocatalytic properties toward a large number of electroactive molecules. For example, PdNP-modified ITO (PdNP-ITO) electrodes have been used as electrocatalysts in the electrochemical reactions of hydrogen, oxygen, hydrogen peroxide (H2O2), ascorbic acid, formic acid, alcohol, nitrite ions, cefotaxime, and hydrazine. See P. Bertoncello, M. Peruffo, P. R. Unwin, “Functional electrochemically-active ultra-thin Nafion films” Colloids and Surfaces A: Physicochem. Eng. Aspects 321 (2008) 222-226, G. Chang, M. Oyama, K. Hirao, “Seed-mediated growth of palladium nanocrystals on indium tin oxide surfaces and their applicability as modified electrodes” J. Phys. Chem. B 110 (2006) 20362-20368, H. Ma, Z. Zhang, H. Pang, S. Li, Y. Chen, W. Zhang, “Fabrication and electrochemical sensing property of a composite film based on a polyoxometalate and palladium nanoparticles” Electrochimica Acta 69 (2012) 379-383, C. Fang, Y. Fan, J. M. Kong, G. J. Zhang, L. Linn, S. Rafeah, “DNA-templated preparation of palladium nanoparticles and their application” Sensors and Actuators B 126 (2007) 684-690, D. Renard, C. McCain, B. Baidoun, A. Bondy, K. Bandyopadhyay, “Electrocatalytic properties of in situ-generated palladium nanoparticle assemblies towards oxidation of multi-carbon alcohols and polyalcohols” Colloids and Surfaces A: Physicochem. Eng. Aspects 463 (2014) 44-54, G. Yang, Y. Yang, Y. Wang, L. Yu, D. Zhou, J. Jia, “Controlled electrochemical behavior of indium tin oxide electrode modified with Pd nanoparticles via electrospinning followed by calcination toward nitrite ions” Electrochimica Acta 78 (2012) 200-204, S. Gupta, R, Prakash, “Ninety Second Electrosynthesis of palladium nanocubes on ITO surface and its application in electrosensing of cefotaxime” Electroanalysis 26 (2014) 2337-2341, and H. Lin, J. Yang, J. Liu, Y. Huang, J. Xiao, X. Zhang, “Properties of Pd nanoparticles-embedded polyaniline multilayer film and its electrocatalytic activity for hydrazine oxidation” Electrochimica Acta 90 (2013) 382-392, each incorporated herein by reference in their entirety.
Previous studies have examined PdNP-modified ITO electrodes in which the modification proceeded through seed-mediated growth. See A. Sangwan, A. Sangwan, M. Yadav, N. Sehrawat, “Seed-mediated growth of palladium nanocrystals on ITO substrate and their characterization” Adv. Appl. Sci. Res. 4 (2013) 138-145, incorporated herein by reference in its entirety. Because small seed PdNPs attach readily onto ITO surfaces, chemical growth treatments can form PdNP-ITO. The seed-mediated growth method requires longer times and multiple chemicals. The electron transfer reactions can be affected by the molecules which are used to functionalize the electrode surface for capturing the Pd precursors. PdNP-ITO has been prepared by electrospinning a Pd precursor, followed by calcination at high temperatures (500° C.) for two hours. Electrodeposition is commonly used to rapidly prepare PdNP-ITOs at room temperature without functionalizing the ITO surfaces. See S. Thiagarajan, R. Yang, S. Chen, “Palladium nanoparticles modified electrode for the selective detection of catecholamine neurotransmitters in presence of ascorbic acid” Bioelectrochemistry 75 (2009) 163-169, Y. Fang, S. Guo, C. Zhu, S. Dong, E. Wang, “Twenty second synthesis of Pd nanourchins with high electrochemical activity through an electrochemical route” Langmuir 26 (2010) 17816-17820, O. I. Kuntyi, P. Y. Stakhira, V. V. Cherpak, O. I. Bilan, Y. V. Okhremchuk, L. Y. Voznyak, N. V. Kostiv, B. Y. Kulyk, Z. Y. Hotra, “Electrochemical depositions of palladium on indium tin oxide-coated glass and their possible application in organic electronics technology” Micro & Nano Letters 6 (2011) 592-595, and V. I. Pokhmurskii, O. I. Kuntyi, S. A. Kornii, O. I. Bilan, E. V. Okhermchuk, “Formation of palladium nanoparticles under pulse current in a dimethylformamide solution” Protection of Metals and Physical Chemistry of Surfaces 47 (2011) 59-62, each incorporated herein by reference in their entirety. The control of NP size and the achievement of a homogeneous distribution of metal NPs across the substrate surface pose challenges in electrodeposition.
In view of the forgoing, one objective of the present invention is to provide a rapid, simple, cost effective, and reliable method for preparing PdNP densely gathered on GZO electrodes which are capable of electrocatalysis of oxidation reactions.